How and when the forecast bulletins are published

The water level and discharge forecast bulletins are published in tabular and graphical form and provide an overview of river data measured in recent hours and forecasts for water and discharge levels.

This information is presented in the form of hourly averages for three calendar days in each case. Forecasts are generally issued at around 8.30 a.m. on working days. If a specified discharge threshold is exceeded or is forecast as likely to be exceeded, the frequency with which forecasts are calculated is increased. Initially, the forecasts are issued twice daily (including weekends and holidays) on reception of the latest MeteoSwiss weather model (approximately 0.6 h UTC and 18 h UTC). During heavy floods, the forecasts are updated every two hours.

How are water level and discharge forecasts are produced?

1. The FOEN forecasting centre collects all of the data required to produce the forecasts: the precipitation and temperatures measured  at the MeteoSwiss SwissMetNet stations, data from numerical forecast models, also produced by  MeteoSwiss, lake water levels and river discharge  data from the FOEN-operated measuring stations. Additional qualitative support is provided by precipitation data obtained using radar images.
2. The raw data must be checked for completeness and plausibility. Any errors found are corrected manually.
3. It is then decided whether lake outflows should be computed using the predefined regulation schedules or whether expected lake outflows should be entered manually, particularly in the case of flood conditions.
4. Data for entire basin areas must be extrapolated from the meteorological point data provided by the measuring stations.
5. Once all of these preparatory measures have been completed, the hydrological model is used to generate the water level and discharge forecasts.
6. The results are published on the internet.